Java使用RSA加密解密签名及校验

小咪咪 2023-06-04 11:58 98阅读 0赞

RSA加密解密类：

import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.FileReader;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.security.InvalidKeyException;
    import java.security.KeyFactory;
    import java.security.KeyPair;
    import java.security.KeyPairGenerator;
    import java.security.NoSuchAlgorithmException;
    import java.security.SecureRandom;
    
    import java.security.interfaces.RSAPrivateKey;
    import java.security.interfaces.RSAPublicKey;
    import java.security.spec.InvalidKeySpecException;
    import java.security.spec.PKCS8EncodedKeySpec;
    import java.security.spec.X509EncodedKeySpec;
     
    import javax.crypto.BadPaddingException;
    import javax.crypto.Cipher;
    import javax.crypto.IllegalBlockSizeException;
    import javax.crypto.NoSuchPaddingException;
    
    import com.fcplay.Base64;
     
    public class RSAEncrypt {
    	/**
    	 * 字节数据转字符串专用集合
    	 */
    	private static final char[] HEX_CHAR = { '0', '1', '2', '3', '4', '5', '6',
    			'7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
     
    	/**
    	 * 随机生成密钥对
    	 */
    	public static void genKeyPair(String filePath) {
    		// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
    		KeyPairGenerator keyPairGen = null;
    		try {
    			keyPairGen = KeyPairGenerator.getInstance("RSA");
    		} catch (NoSuchAlgorithmException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		// 初始化密钥对生成器，密钥大小为96-1024位
    		keyPairGen.initialize(1024,new SecureRandom());
    		// 生成一个密钥对，保存在keyPair中
    		KeyPair keyPair = keyPairGen.generateKeyPair();
    		// 得到私钥
    		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
    		// 得到公钥
    		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
    		try {
    			// 得到公钥字符串
    			String publicKeyString = Base64.encode(publicKey.getEncoded());
    			// 得到私钥字符串
    			String privateKeyString = Base64.encode(privateKey.getEncoded());
    			// 将密钥对写入到文件
    			FileWriter pubfw = new FileWriter(filePath + "/publicKey.keystore");
    			FileWriter prifw = new FileWriter(filePath + "/privateKey.keystore");
    			BufferedWriter pubbw = new BufferedWriter(pubfw);
    			BufferedWriter pribw = new BufferedWriter(prifw);
    			pubbw.write(publicKeyString);
    			pribw.write(privateKeyString);
    			pubbw.flush();
    			pubbw.close();
    			pubfw.close();
    			pribw.flush();
    			pribw.close();
    			prifw.close();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
     
    	/**
    	 * 从文件中输入流中加载公钥
    	 * @param in 公钥输入流
    	 * @throws Exception 加载公钥时产生的异常
    	 */
    	public static String loadPublicKeyByFile(String path) throws Exception {
    		try {
    			BufferedReader br = new BufferedReader(new FileReader(path
    					+ "/publicKey.keystore"));
    			String readLine = null;
    			StringBuilder sb = new StringBuilder();
    			while ((readLine = br.readLine()) != null) {
    				sb.append(readLine);
    			}
    			br.close();
    			return sb.toString();
    		} catch (IOException e) {
    			throw new Exception("公钥数据流读取错误");
    		} catch (NullPointerException e) {
    			throw new Exception("公钥输入流为空");
    		}
    	}
     
    	/**
    	 * 从字符串中加载公钥
    	 * @param publicKeyStr 公钥数据字符串
    	 * @throws Exception 加载公钥时产生的异常
    	 */
    	public static RSAPublicKey loadPublicKeyByStr(String publicKeyStr)
    			throws Exception {
    		try {
    			byte[] buffer = Base64.decode(publicKeyStr);
    			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    			X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
    			return (RSAPublicKey) keyFactory.generatePublic(keySpec);
    		} catch (NoSuchAlgorithmException e) {
    			throw new Exception("无此算法");
    		} catch (InvalidKeySpecException e) {
    			throw new Exception("公钥非法");
    		} catch (NullPointerException e) {
    			throw new Exception("公钥数据为空");
    		}
    	}
     
    	/**
    	 * 从文件中加载私钥
    	 * @param keyFileName 私钥文件名
    	 * @return 是否成功
    	 * @throws Exception
    	 */
    	public static String loadPrivateKeyByFile(String path) throws Exception {
    		try {
    			BufferedReader br = new BufferedReader(new FileReader(path
    					+ "/privateKey.keystore"));
    			String readLine = null;
    			StringBuilder sb = new StringBuilder();
    			while ((readLine = br.readLine()) != null) {
    				sb.append(readLine);
    			}
    			br.close();
    			return sb.toString();
    		} catch (IOException e) {
    			throw new Exception("私钥数据读取错误");
    		} catch (NullPointerException e) {
    			throw new Exception("私钥输入流为空");
    		}
    	}
     
    	public static RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr)
    			throws Exception {
    		try {
    			byte[] buffer = Base64.decode(privateKeyStr);
    			PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
    			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    			return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
    		} catch (NoSuchAlgorithmException e) {
    			throw new Exception("无此算法");
    		} catch (InvalidKeySpecException e) {
    			throw new Exception("私钥非法");
    		} catch (NullPointerException e) {
    			throw new Exception("私钥数据为空");
    		}
    	}
     
    	/**
    	 * 公钥加密过程
    	 * @param publicKey 公钥
    	 * @param plainTextData 明文数据
    	 * @return
    	 * @throws Exception 加密过程中的异常信息
    	 */
    	public static byte[] encrypt(RSAPublicKey publicKey, byte[] plainTextData)
    			throws Exception {
    		if (publicKey == null) {
    			throw new Exception("加密公钥为空, 请设置");
    		}
    		Cipher cipher = null;
    		try {
    			// 使用默认RSA
    			cipher = Cipher.getInstance("RSA");
    			// cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
    			cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    			byte[] output = cipher.doFinal(plainTextData);
    			return output;
    		} catch (NoSuchAlgorithmException e) {
    			throw new Exception("无此加密算法");
    		} catch (NoSuchPaddingException e) {
    			e.printStackTrace();
    			return null;
    		} catch (InvalidKeyException e) {
    			throw new Exception("加密公钥非法,请检查");
    		} catch (IllegalBlockSizeException e) {
    			throw new Exception("明文长度非法");
    		} catch (BadPaddingException e) {
    			throw new Exception("明文数据已损坏");
    		}
    	}
     
    	/**
    	 * 私钥加密过程
    	 * @param privateKey 私钥
    	 * @param plainTextData 明文数据
    	 * @return
    	 * @throws Exception 加密过程中的异常信息
    	 */
    	public static byte[] encrypt(RSAPrivateKey privateKey, byte[] plainTextData)
    			throws Exception {
    		if (privateKey == null) {
    			throw new Exception("加密私钥为空, 请设置");
    		}
    		Cipher cipher = null;
    		try {
    			// 使用默认RSA
    			cipher = Cipher.getInstance("RSA");
    			cipher.init(Cipher.ENCRYPT_MODE, privateKey);
    			byte[] output = cipher.doFinal(plainTextData);
    			return output;
    		} catch (NoSuchAlgorithmException e) {
    			throw new Exception("无此加密算法");
    		} catch (NoSuchPaddingException e) {
    			e.printStackTrace();
    			return null;
    		} catch (InvalidKeyException e) {
    			throw new Exception("加密私钥非法,请检查");
    		} catch (IllegalBlockSizeException e) {
    			throw new Exception("明文长度非法");
    		} catch (BadPaddingException e) {
    			throw new Exception("明文数据已损坏");
    		}
    	}
     
    	/**
    	 * 私钥解密过程
    	 * @param privateKey 私钥
    	 * @param cipherData 密文数据
    	 * @return 明文
    	 * @throws Exception 解密过程中的异常信息
    	 */
    	public static byte[] decrypt(RSAPrivateKey privateKey, byte[] cipherData)
    			throws Exception {
    		if (privateKey == null) {
    			throw new Exception("解密私钥为空, 请设置");
    		}
    		Cipher cipher = null;
    		try {
    			// 使用默认RSA
    			cipher = Cipher.getInstance("RSA");
    			// cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
    			cipher.init(Cipher.DECRYPT_MODE, privateKey);
    			byte[] output = cipher.doFinal(cipherData);
    			return output;
    		} catch (NoSuchAlgorithmException e) {
    			throw new Exception("无此解密算法");
    		} catch (NoSuchPaddingException e) {
    			e.printStackTrace();
    			return null;
    		} catch (InvalidKeyException e) {
    			throw new Exception("解密私钥非法,请检查");
    		} catch (IllegalBlockSizeException e) {
    			throw new Exception("密文长度非法");
    		} catch (BadPaddingException e) {
    			throw new Exception("密文数据已损坏");
    		}
    	}
     
    	/**
    	 * 公钥解密过程
    	 * @param publicKey 公钥
    	 * @param cipherData 密文数据
    	 * @return 明文
    	 * @throws Exception 解密过程中的异常信息
    	 */
    	public static byte[] decrypt(RSAPublicKey publicKey, byte[] cipherData)
    			throws Exception {
    		if (publicKey == null) {
    			throw new Exception("解密公钥为空, 请设置");
    		}
    		Cipher cipher = null;
    		try {
    			// 使用默认RSA
    			cipher = Cipher.getInstance("RSA");
    			// cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
    			cipher.init(Cipher.DECRYPT_MODE, publicKey);
    			byte[] output = cipher.doFinal(cipherData);
    			return output;
    		} catch (NoSuchAlgorithmException e) {
    			throw new Exception("无此解密算法");
    		} catch (NoSuchPaddingException e) {
    			e.printStackTrace();
    			return null;
    		} catch (InvalidKeyException e) {
    			throw new Exception("解密公钥非法,请检查");
    		} catch (IllegalBlockSizeException e) {
    			throw new Exception("密文长度非法");
    		} catch (BadPaddingException e) {
    			throw new Exception("密文数据已损坏");
    		}
    	}
     
    	/**
    	 * 字节数据转十六进制字符串
    	 * @param data 输入数据
    	 * @return 十六进制内容
    	 */
    	public static String byteArrayToString(byte[] data) {
    		StringBuilder stringBuilder = new StringBuilder();
    		for (int i = 0; i < data.length; i++) {
    			// 取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移
    			stringBuilder.append(HEX_CHAR[(data[i] & 0xf0) >>> 4]);
    			// 取出字节的低四位 作为索引得到相应的十六进制标识符
    			stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
    			if (i < data.length - 1) {
    				stringBuilder.append(' ');
    			}
    		}
    		return stringBuilder.toString();
    	}
    }

签名及校验类：

import java.security.KeyFactory;
    import java.security.PrivateKey;
    import java.security.PublicKey;
    import java.security.spec.PKCS8EncodedKeySpec;
    import java.security.spec.X509EncodedKeySpec;
     
    /**
     * RSA签名验签类
     */
    public class RSASignature{
    	
    	/**
    	 * 签名算法
    	 */
    	public static final String SIGN_ALGORITHMS = "SHA1WithRSA";
     
    	/**
    	* RSA签名
    	* @param content 待签名数据
    	* @param privateKey 商户私钥
    	* @param encode 字符集编码
    	* @return 签名值
    	*/
    	public static String sign(String content, String privateKey, String encode)
    	{
            try 
            {
            	PKCS8EncodedKeySpec priPKCS8 	= new PKCS8EncodedKeySpec( Base64.decode(privateKey) ); 
            	
            	KeyFactory keyf 				= KeyFactory.getInstance("RSA");
            	PrivateKey priKey 				= keyf.generatePrivate(priPKCS8);
     
                java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
     
                signature.initSign(priKey);
                signature.update( content.getBytes(encode));
     
                byte[] signed = signature.sign();
                
                return Base64.encode(signed);
            }
            catch (Exception e) 
            {
            	e.printStackTrace();
            }
            
            return null;
        }
    	
    	public static String sign(String content, String privateKey)
    	{
            try 
            {
            	PKCS8EncodedKeySpec priPKCS8 	= new PKCS8EncodedKeySpec( Base64.decode(privateKey) ); 
            	KeyFactory keyf = KeyFactory.getInstance("RSA");
            	PrivateKey priKey = keyf.generatePrivate(priPKCS8);
                java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
                signature.initSign(priKey);
                signature.update( content.getBytes());
                byte[] signed = signature.sign();
                return Base64.encode(signed);
            }
            catch (Exception e) 
            {
            	e.printStackTrace();
            }
            return null;
        }
    	
    	/**
    	* RSA验签名检查
    	* @param content 待签名数据
    	* @param sign 签名值
    	* @param publicKey 分配给开发商公钥
    	* @param encode 字符集编码
    	* @return 布尔值
    	*/
    	public static boolean doCheck(String content, String sign, String publicKey,String encode)
    	{
    		try 
    		{
    			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    	        byte[] encodedKey = Base64.decode(publicKey);
    	        PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
     
    		
    			java.security.Signature signature = java.security.Signature
    			.getInstance(SIGN_ALGORITHMS);
    		
    			signature.initVerify(pubKey);
    			signature.update( content.getBytes(encode) );
    		
    			boolean bverify = signature.verify( Base64.decode(sign) );
    			return bverify;
    			
    		} 
    		catch (Exception e) 
    		{
    			e.printStackTrace();
    		}
    		
    		return false;
    	}
    	
    	public static boolean doCheck(String content, String sign, String publicKey)
    	{
    		try 
    		{
    			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    	        byte[] encodedKey = Base64.decode(publicKey);
    	        PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
     
    		
    			java.security.Signature signature = java.security.Signature
    			.getInstance(SIGN_ALGORITHMS);
    		
    			signature.initVerify(pubKey);
    			signature.update( content.getBytes() );
    		
    			boolean bverify = signature.verify( Base64.decode(sign) );
    			return bverify;
    			
    		} 
    		catch (Exception e) 
    		{
    			e.printStackTrace();
    		}
    		
    		return false;
    	}
    }

再来一个Base64的类，当然你也可以用commons-codec-1.9.jar

package com.ihep;
     
    public final class Base64 {
     
        static private final int     BASELENGTH           = 128;
        static private final int     LOOKUPLENGTH         = 64;
        static private final int     TWENTYFOURBITGROUP   = 24;
        static private final int     EIGHTBIT             = 8;
        static private final int     SIXTEENBIT           = 16;
        static private final int     FOURBYTE             = 4;
        static private final int     SIGN                 = -128;
        static private final char    PAD                  = '=';
        static private final boolean fDebug               = false;
        static final private byte[]  base64Alphabet       = new byte[BASELENGTH];
        static final private char[]  lookUpBase64Alphabet = new char[LOOKUPLENGTH];
     
        static {
            for (int i = 0; i < BASELENGTH; ++i) {
                base64Alphabet[i] = -1;
            }
            for (int i = 'Z'; i >= 'A'; i--) {
                base64Alphabet[i] = (byte) (i - 'A');
            }
            for (int i = 'z'; i >= 'a'; i--) {
                base64Alphabet[i] = (byte) (i - 'a' + 26);
            }
     
            for (int i = '9'; i >= '0'; i--) {
                base64Alphabet[i] = (byte) (i - '0' + 52);
            }
     
            base64Alphabet['+'] = 62;
            base64Alphabet['/'] = 63;
     
            for (int i = 0; i <= 25; i++) {
                lookUpBase64Alphabet[i] = (char) ('A' + i);
            }
     
            for (int i = 26, j = 0; i <= 51; i++, j++) {
                lookUpBase64Alphabet[i] = (char) ('a' + j);
            }
     
            for (int i = 52, j = 0; i <= 61; i++, j++) {
                lookUpBase64Alphabet[i] = (char) ('0' + j);
            }
            lookUpBase64Alphabet[62] = (char) '+';
            lookUpBase64Alphabet[63] = (char) '/';
     
        }
     
        private static boolean isWhiteSpace(char octect) {
            return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
        }
     
        private static boolean isPad(char octect) {
            return (octect == PAD);
        }
     
        private static boolean isData(char octect) {
            return (octect < BASELENGTH && base64Alphabet[octect] != -1);
        }
     
        /**
         * Encodes hex octects into Base64
         *
         * @param binaryData Array containing binaryData
         * @return Encoded Base64 array
         */
        public static String encode(byte[] binaryData) {
     
            if (binaryData == null) {
                return null;
            }
     
            int lengthDataBits = binaryData.length * EIGHTBIT;
            if (lengthDataBits == 0) {
                return "";
            }
     
            int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
            int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
            int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
            char encodedData[] = null;
     
            encodedData = new char[numberQuartet * 4];
     
            byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
     
            int encodedIndex = 0;
            int dataIndex = 0;
            if (fDebug) {
                System.out.println("number of triplets = " + numberTriplets);
            }
     
            for (int i = 0; i < numberTriplets; i++) {
                b1 = binaryData[dataIndex++];
                b2 = binaryData[dataIndex++];
                b3 = binaryData[dataIndex++];
     
                if (fDebug) {
                    System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
                }
     
                l = (byte) (b2 & 0x0f);
                k = (byte) (b1 & 0x03);
     
                byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
                byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
                byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
     
                if (fDebug) {
                    System.out.println("val2 = " + val2);
                    System.out.println("k4   = " + (k << 4));
                    System.out.println("vak  = " + (val2 | (k << 4)));
                }
     
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
            }
     
            // form integral number of 6-bit groups
            if (fewerThan24bits == EIGHTBIT) {
                b1 = binaryData[dataIndex];
                k = (byte) (b1 & 0x03);
                if (fDebug) {
                    System.out.println("b1=" + b1);
                    System.out.println("b1<<2 = " + (b1 >> 2));
                }
                byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
                encodedData[encodedIndex++] = PAD;
                encodedData[encodedIndex++] = PAD;
            } else if (fewerThan24bits == SIXTEENBIT) {
                b1 = binaryData[dataIndex];
                b2 = binaryData[dataIndex + 1];
                l = (byte) (b2 & 0x0f);
                k = (byte) (b1 & 0x03);
     
                byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
                byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
     
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
                encodedData[encodedIndex++] = PAD;
            }
     
            return new String(encodedData);
        }
     
        /**
         * Decodes Base64 data into octects
         *
         * @param encoded string containing Base64 data
         * @return Array containind decoded data.
         */
        public static byte[] decode(String encoded) {
     
            if (encoded == null) {
                return null;
            }
     
            char[] base64Data = encoded.toCharArray();
            // remove white spaces
            int len = removeWhiteSpace(base64Data);
     
            if (len % FOURBYTE != 0) {
                return null;//should be divisible by four
            }
     
            int numberQuadruple = (len / FOURBYTE);
     
            if (numberQuadruple == 0) {
                return new byte[0];
            }
     
            byte decodedData[] = null;
            byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
            char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
     
            int i = 0;
            int encodedIndex = 0;
            int dataIndex = 0;
            decodedData = new byte[(numberQuadruple) * 3];
     
            for (; i < numberQuadruple - 1; i++) {
     
                if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
                    || !isData((d3 = base64Data[dataIndex++]))
                    || !isData((d4 = base64Data[dataIndex++]))) {
                    return null;
                }//if found "no data" just return null
     
                b1 = base64Alphabet[d1];
                b2 = base64Alphabet[d2];
                b3 = base64Alphabet[d3];
                b4 = base64Alphabet[d4];
     
                decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
            }
     
            if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
                return null;//if found "no data" just return null
            }
     
            b1 = base64Alphabet[d1];
            b2 = base64Alphabet[d2];
     
            d3 = base64Data[dataIndex++];
            d4 = base64Data[dataIndex++];
            if (!isData((d3)) || !isData((d4))) {//Check if they are PAD characters
                if (isPad(d3) && isPad(d4)) {
                    if ((b2 & 0xf) != 0)//last 4 bits should be zero
                    {
                        return null;
                    }
                    byte[] tmp = new byte[i * 3 + 1];
                    System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                    tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                    return tmp;
                } else if (!isPad(d3) && isPad(d4)) {
                    b3 = base64Alphabet[d3];
                    if ((b3 & 0x3) != 0)//last 2 bits should be zero
                    {
                        return null;
                    }
                    byte[] tmp = new byte[i * 3 + 2];
                    System.arraycopy(decodedData, 0, tmp, 0, i * 3);
                    tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                    tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                    return tmp;
                } else {
                    return null;
                }
            } else { //No PAD e.g 3cQl
                b3 = base64Alphabet[d3];
                b4 = base64Alphabet[d4];
                decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
     
            }
     
            return decodedData;
        }
     
        /**
         * remove WhiteSpace from MIME containing encoded Base64 data.
         *
         * @param data  the byte array of base64 data (with WS)
         * @return      the new length
         */
        private static int removeWhiteSpace(char[] data) {
            if (data == null) {
                return 0;
            }
     
            // count characters that's not whitespace
            int newSize = 0;
            int len = data.length;
            for (int i = 0; i < len; i++) {
                if (!isWhiteSpace(data[i])) {
                    data[newSize++] = data[i];
                }
            }
            return newSize;
        }
    }

测试类MainTest：

public class MainTest {
     
    	public static void main(String[] args) throws Exception {
    		String filepath="G:/tmp/";
     
    		//RSAEncrypt.genKeyPair(filepath);
    		
    		System.out.println("--------------公钥加密私钥解密过程-------------------");
    		String plainText="ihep_公钥加密私钥解密";
    		//公钥加密过程
    		byte[] cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)),plainText.getBytes());
    		String cipher=Base64.encode(cipherData);
    		//私钥解密过程
    		byte[] res=RSAEncrypt.decrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)), Base64.decode(cipher));
    		String restr=new String(res);
    		System.out.println("原文："+plainText);
    		System.out.println("加密："+cipher);
    		System.out.println("解密："+restr);
    		System.out.println();
    		
    		System.out.println("--------------私钥加密公钥解密过程-------------------");
    		plainText="ihep_私钥加密公钥解密";
    		//私钥加密过程
    		cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)),plainText.getBytes());
    		cipher=Base64.encode(cipherData);
    		//公钥解密过程
    		res=RSAEncrypt.decrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)), Base64.decode(cipher));
    		restr=new String(res);
    		System.out.println("原文："+plainText);
    		System.out.println("加密："+cipher);
    		System.out.println("解密："+restr);
    		System.out.println();
    		
    		System.out.println("---------------私钥签名过程------------------");
    		String content="ihep_这是用于签名的原始数据";
    		String signstr=RSASignature.sign(content,RSAEncrypt.loadPrivateKeyByFile(filepath));
    		System.out.println("签名原串："+content);
    		System.out.println("签名串："+signstr);
    		System.out.println();
    		
    		System.out.println("---------------公钥校验签名------------------");
    		System.out.println("签名原串："+content);
    		System.out.println("签名串："+signstr);
    		
    		System.out.println("验签结果："+RSASignature.doCheck(content, signstr, RSAEncrypt.loadPublicKeyByFile(filepath)));
    		System.out.println();
    	}
    }

看看运行截图：

![Center][]

![Center 1][]

[Center]: /images/20230601/e5838912b4be49478a2ec1e480ecd672.png
[Center 1]: /images/20230601/31bd3ad952b6452595ac7a9c80347033.png